Refrigeration systems with condenser by-pass means



y 26, 1964 R. w. JOHNSON 3,134,241

REFRIGERATION SYSTEMS WITH CONDENSER BY-PASS MEANS Filed. Oct. 4, 1962 FIG. I

FIG. 2

IN VEN TOR.

ROBERT W. JOHNSON ATTORNEY.

United States Patent 3,134,241 REFRlGERATIGN SYSTEMS WITH CONDENSER BIZ-PASS MEANS Robert W. Johnson, De Witt, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Oct. 4, 1962, Ser. No. 228,374 7 Claims. (Cl. 62-196) The present invention relates to an improved refrigeration system and more particularly to a refrigeration system which will provide satisfactory operation under low ambient temperature conditions which produce low condenser or head pressures.

A conventional refrigeration system includes a closed circuit having a compressor, condenser, expansion means and evaporator in series. Refrigerant is pumped by the compressor to the condenser wherein the heat of compression and evaporation is removed by heat exchange between the condensing gases in the condenser and a cooling medium such as the ambient air. However, under normal operating conditions within a predetermined range of ambient temperatures, the refrigerant in the condenser, after said cooling has occurred, remains at a sufliciently high pressure to force the liquefied refrigerant through the expansion means. Thereafter, heat is absorbed from the area in which the evaporator is located, thus changing the refrigerant from a liquid to a gas in the evaporator. However, when the ambient temperature of the air, which is utilized to cool the compressed gases in the condenser, drops below said predetermined range of temperatures, the gases in the condenser condense to a relatively great extent and a condition may arise where there is insufiicient pressure in the condenser to effect proper flow of the refrigerant through the expansion means leading to the evaporator.

In the past there have been various ways of overcoming the foregoing operational deficiency of the refrigeration system, including the artificial raising of the condenser pressure to a value which was suflicient to cause liquid refrigerant to pass through the expansion means in the required manner. Generally, the condenser pressure was raised by causing the hang up of liquid refrigerant in.

the condenser, thereby effectively reducing the condenser surface and maintaining the temperature and therefore "ice The improvedrefrigeration system of the present invention includes a conventional refrigeration system havthe pressure of refrigerant in said condenser at a sufficiently high value for proper operation of the expansion means. manner had certain shortcomings, namely, that-an ad -.ditional' amount of refrigerant was required in the system when a portion thereof was utilized solely for the purpose of blocking off a portion of the condenser while additional control means were required.

The primary object of the present invention is to provide a refrigeration system which will operate satisfactori- Raising-the condenser pressure in the foregoing I ly under low ambient temperature conditions which pro- 7 duce low condenser pressures. It is another object of the present invention to provide an improved refrigeration system in which there is effective isolation between the compressor and the con- 7 denser so that the condenser may operate at low temperatures and pressures corresponding to the cooling temperature thereof without being detrimentally influenced by the pressure produced by the compressor, thereby increasing the efficiency of the refrigeration system.

A related object of the present invention is to provide an improved refrigeration system in which there is effecing a compressor, condenser, expansion means and'an evaporator connected in series circuit relationship. In addition, an ejector is provided which has its inlet in communication with the outlet of the condenser, said ejector also having its nozzle adapted for selective communication with the compressor outlet. When the refrigeration system operates in its normal manner, that is, with the condenser pressure being above a predetermined minimum value, as determined by the condensing occurring nozzle and there will then'be a flow to both said ejector nozzle and said condenser from the compressor. The refrigerant routed to the condenser will remain at a low pressure corresponding to the condensing temperature thereof because the portion of refrigerant passed to the ejector nozzle from the compressor causes said ejector to act as a pump which exhausts liquid refrigerant from said condenser. In addition, the pumping action of the ejector also raises the pressure of refrigerant for proper operation of said expansion means. Because of the use of the ejector to raise the pressure to the expansion means, there is no requirement for excess refrigerant in the system inasmuch as refrigerant hang up in the condenser is not utilized for raising the pressure thereof. The present invention will be more fully understood when the following portions of the specification are read in conjunction with the accompanying drawings wherein:

FIGURE 1 is a schematic view ofa refrigeration system embodying the present invention; and I FIGURE 2 is a fragmentary'schematic view of a modification of a portion of the system of FIGURE 1.

In FIGURE 1 a refrigeration system is shown having a compressor 10 for compressing gaseous refrigerant and transmitting it through line 11, valve 12, and line 13 to condenser inlet header 14 from which it passes through condenser coils 15 and 16 to condenser outlet header17. As is well understood in the art, the passage of ambient air, effected by the operation of fan 18, over condenser coils 15, 16 will cause the'compressed'gaseous refrigerant to be condensed in said condenser. Liquid refrigerant leaving condenser outlet header 17 passes through line 19 into the inlet 20 of ejector 21 and thereafter passes through condenser and/or subcooler coil 22 and'line 23 to thermal expansion valve 24 which has" a temperature sensing bulb 25 in contact with the outlet portion of evaporator 26, bulb 25 being connected to valve 24 through capillary 27. The condition of refrigerant leaving evaporator 26 will determine the opening of thermal expansion valve 24. After refrigerant passes through 7 thermal expansion valve 24, it passes into line 28 leading to evaporator 26 located in the area to be cooled, and heat is absorbed from this area thus evaporating the refrigerant. A'fan 37 is associated with evaporator 26 for passing air from the area to be cooled into' heatexchange relation with refrigerant in, the evaporator. A line 29 effects communication between the outlet of evaporator 26 and the inletof compressor 10. It will be understood the evaporator may be employed to 'cool'any gaseous or liquid medium and is not limited to use with a fan.

The above described operation of the refrigeration system of FIGURE 1 occurs when the temperature of the In the event that ambient air utilized for cooling the condenser coils is above a value which will cause the pressure of refrigerant in said condenser to also be above a predetermined minimum value which is sufiicient for proper operation of expansion valve 24. During the foregoing type of operation, ejector 21 merely acts as a refrigerant passageway for passing refrigerant from condenser outlet header 17 to coil 22, and the latter merely serves to provide additional condensing and/ or subcooling capacity.

However, there are times when the ambient air temperature falls to a value at which the saturation pressure of refrigerant in condenser coils 15, 16 is below the predetermined minimum value required for proper operation of expansion valve 2 3. In accordance with the present invention, valve 12 between lines 11 and 13, is a threeway modulating valve which permits a-certain portion of gaseous refrigerant in line 11 to pass to nozzle 30 of ejector 21 through line 31 and a portion of refrigerant to pass into line 13 leading to condenser header 14, under the foregoing low ambient temperature conditions. No refrigerant passes through line 31 to ejector nozzle 30 when the normal condenser pressure is suflicient for proper operation of thermal expansion valve 24. The modulation of valve 12, leading to lines 13 and 31, is controlled by the temperature of refrigerant in line 23 leading to thermal expansion valve 24 because temperature sensing bulb 32, which is in contact with line 23, is in communication with modulating valve 12 through capillary 33. The forcing of gaseous refrigerant through line 31 and nozzle 30 in the foregoing manner causes ejector 21 to act as a pump to exhaust liquid refrigerant from condenser header 17 and thereby lower the condenser pressure and also to raise the pressure of refrigerant transmitted to thermal expansion valve 24.

The modulation of the valve 12 leading to line 13, in conjunction with the action of ejector 21, tends to isolate compressor from the condenser to thereby prevent the condenser pressure from being raised above a value corresponding to the condensing temperature thereof. In other words, the operational characteristics of ejector 21 contribute toward determining the pressure and temperature within the condenser, that is, by exhausting the condenser, ejector 21 permits condensing to occur in said condenser at a relatively low temperature and pressure. Since condensing occurs at a relatively low temperature and therefore at a relatively lowpressure, compressor 14 does not have to work against an increased condenser pressure but may operate at relatively low pressures, thereby reducing its electricity requirements.

Coil 22 is provided at the outlet of ejector 21 for condensing and/or subcooling the mixture of gaseous and liquid refrigerant which passes through ejector 21 during the above described type of operation. Since it is possible, by the proper proportioning of gaseous and liquid refrigerant at the ejector, to obtain a higher pressure leaving the ejector than is obtained from the compressor, coil 22 serves to provide the optimum temperature and pressure conditions of the refrigerant transmitted to expansion valve 24.

It will readily be appreciated that in lieu of a temperature sensing control 32 located at the inlet to expansion valve 24- for controlling the modulation of valve 12, a pressure responsive connection at the line leading to the expansion valve may also be used. If desired, modulating valve 12 may be controlled from any other suitable portion or portions of the refrigeration circuit.

In FIGURE 2 a modified embodiment of the invention shown in FIGUREl is disclosed. A solenoidoperated valve 34 is placed in line 19 leading from condenser outlet header 17. Whenever compressor 19 is off either because the circuit between L and L is opened by the operation of main switch 35 or is opened by the operation of any of the refrigeration controls in the system (not shown) between R and R solenoid 36 will be deenergized to thereby cause valve 34 to close. This prevents liquid refrigerant from being drained from outlet header 17. When the compressor 16 is started again, energization of solenoid 36 will open valve 34 to permit the ready supply of liquid refrigerant within condenser outlet header 17.

While preferred embodiments of the present invention have been disclosed, it will readily be understood that the present invention is not limited thereto, but may be otherwise embodied within the scope of the following claims.

i claim:

1. A refrigeration system comprising a compressor, a condenser, expansion means and an evaporator connected in series circuit relationship, valve means interposed between said compressor and said condenser, pump means interposed between said condenser and said expansion means, and control means operative when said condenser pressure falls below a predetermined-minimum value sufficient for proper operation of said expansion means for actuating the valve to direct a portion of the refrigerant passing therethrough to the pump means thereby actuating said pump means to raise the pressure of refrigerant transmitted to said expansion means from said condenser to a value suflicient for proper operation of said expansion means without raising the pressure of said condenser thereby causing the condensing temperature and pressure to be substantially independent of the compressor pressure.

2. A refrigeration system comprising a compressor, a condenser, expansion means and an evaporator con nected in series circuit relationship, valve means interposed between said compressor and said condenser, pump means interposed between said condenser and said expansion means, and control means operative when said condenser pressure falls below a predetermined minimum vaiue sufficient for proper operation of said expansion means for both controiiing the how of refrigerant through said valve means between said compressor and condenser and for causing said pump means to raise the pressure of refrigerant transmitted to said expansion means from said condenser to a value sufiicient for proper operation of said expansion means without raising the pressure of said condenser, therebyeffectively isolating said condenser from said compressor by tending to cause the condensing temperature and pressure to be independent of the compressor pressure, said pump means comprising an ejector having a nozzle and an inlet, means for effecting communication between said condenser and said inlet of said ejector, said control means including means for effecting communication between said nozzle and said compressor whereby a portion of the flow of refrigerant from said compressor causes said ejector to pum liquid refrigerant from said condenser.

3. A refrigeration system as set forth in claim 2 including a coil operatively interposed between said ejector and said expansion means for treating refrigerant leaving said ejector.

4. A refrigeration system as set forth in claim'2 wherein said valve means modulate the flow from said compressor to both said condenser and said ejector inresponse to a condition of the refrigeration system. I

5. A refrigeration system as set forth in claim 4 where- 1 in said control means are responsive to the temperature of refrigerant entering said expansion means. 7

6. A refrigeration system comprising a compressor, a condenser, expansion means and an evaporator connected in series circuit relationship, means for passing a cooling medium through said condenser in heat exchange relation with refrigerant therein, control means for auto maticaliy permitting flow of refrigerant through said refrigeration system when said condenser pressure is above a predetermined minimum value sufficient for proper operation of said expansion means, an ejector having a nozzle and an inlet, said control means automaticaily' effecting communication between said ejector nozzle and said compressor and effectively isolating said condenser from said compressor While permitting flow of refrigerant therebetween when the pressure in said condenser falls below said predetermined minimum value sufficient for proper operation of said expansion means whereby condensing of refrigerant may occur in said condenser at a pressure corresponding to the temperature produced by the cooling medium being utilized to cool said condenser and whereby the communication between said compressor and said nozzle causes liquid refrigerant to be drawn from said condenser and passed to said expansion means at a pressure sufficient for proper operation of said expansion means without raising the pressure of refrigerant in said condenser.

7. A refrigeration systemcomprising a compressor, a condenser, expansion means and an evaporator connected in series circuit relationship, an ejector having a nozzle and an inlet, means for effecting communication between said condenser and said inlet of said ejector, and con trol means for automatically permitting the flow of refrigerant from said condenser to said expansion means through said ejector inlet when said condenser pressure is above a predetermined minimum value sufiicient for proper operation of said expansion means whereby said ejector merely serves as a conduit for transmitting refrigerant from said condenser to said expansion means, said control means automatically effecting communication between said ejector nozzle and said compressor when the pressure in said condenser falls below said predetermined minimum value whereby said control means in conjunction with said ejector effectively isolate said condenser from said compressor while permitting flow of refrigerant therebetween thereby permitting the condenser temperature and pressure to be independent of the compressor pressure, said communication between said ejector nozzle and said compressor causing said ejector to raise the pressure of refrigerant transmitted to said expansion means from said condenser while lowering the pressure in said condenser.

References Cited in the file of this patent UNITED STATES PATENTS Schenk June 6, 1961 

1. A REFRIGERATION SYSTEM COMPRISING A COMPRESSOR, A CONDENSER, EXPANSION MEANS AND AN EVAPORATOR CONNECTED IN SERIES CIRCUIT RELATIONSHIP, VALVE MEANS INTERPOSED BETWEEN SAID COMPRESSOR AND SAID CONDENSER, PUMP MEANS INTERPOSED BETWEEN SAID CONDENSER AND SAID EXPANSION MEANS, AND CONTROL MEANS OPERATIVE WHEN SAID CONDENSER PRESSURE FALLS BELOW A PREDETERMINED MINIMUM VALUE SUFFICIENT FOR PROPER OPERATION OF SAID EXPANSION MEANS FOR ACTUATING THE VALVE TO DIRECT A PORTION OF THE REFRIGERANT PASSING THERETHROUGH TO THE PUMP MEANS THEREBY ACTUATING SAID PUMP MEANS TO RAISE THE PRESSURE OF REFRIGERANT TRANSMITTED TO SAID EXPANSION MEANS FROM SAID CONDENSER 